Allow the current for both RED and IR LEDs to be set via an device tree
property setting.
This is an optional setting that is useful for applications that have a
known glass attenuation factor.
Signed-off-by: Matt Ranostay <mranos...@gmail.com>
---
Changes from v2:
* change to use microamp property name from LED class
* updated documentation for new format
* added allowed current index map
.../devicetree/bindings/iio/health/max30100.txt | 8 +++
drivers/iio/health/max30100.c | 81 ++++++++++++++++++++--
2 files changed, 83 insertions(+), 6 deletions(-)
diff --git a/Documentation/devicetree/bindings/iio/health/max30100.txt
b/Documentation/devicetree/bindings/iio/health/max30100.txt
index f6fbac6..4eef96e 100644
--- a/Documentation/devicetree/bindings/iio/health/max30100.txt
+++ b/Documentation/devicetree/bindings/iio/health/max30100.txt
@@ -11,11 +11,19 @@ Required properties:
Refer to interrupt-controller/interrupts.txt for generic
interrupt client node bindings.
+Optional properties:
+ - maxim,led-current-microamp: configuration for LED current in microamperes
+ while the engine is running. First indexed value is the configuration for
+ the RED LED, and second value is for the IR LED.
+
+ Refer to the datasheet for the allowed current values.
+
Example:
max30100@057 {
compatible = "maxim,max30100";
reg = <57>;
+ maxim,led-current-microamp = <24000 50000>;
interrupt-parent = <&gpio1>;
interrupts = <16 2>;
};
diff --git a/drivers/iio/health/max30100.c b/drivers/iio/health/max30100.c
index 9d1c81f..09db893 100644
--- a/drivers/iio/health/max30100.c
+++ b/drivers/iio/health/max30100.c
@@ -13,7 +13,7 @@
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
- * TODO: allow LED current and pulse length controls via device tree properties
+ * TODO: enable pulse length controls via device tree properties
*/
#include <linux/module.h>
@@ -24,6 +24,7 @@
#include <linux/irq.h>
#include <linux/i2c.h>
#include <linux/mutex.h>
+#include <linux/of.h>
#include <linux/regmap.h>
#include <linux/iio/iio.h>
#include <linux/iio/buffer.h>
@@ -65,6 +66,7 @@
#define MAX30100_REG_SPO2_CONFIG_1600US 0x3
#define MAX30100_REG_LED_CONFIG 0x09
+#define MAX30100_REG_LED_CONFIG_LED_MASK 0x0f
#define MAX30100_REG_LED_CONFIG_RED_LED_SHIFT 4
#define MAX30100_REG_LED_CONFIG_24MA 0x07
@@ -111,6 +113,12 @@ static const struct regmap_config max30100_regmap_config =
{
.volatile_reg = max30100_is_volatile_reg,
};
+static const unsigned int max30100_led_current_mapping[] = {
+ 4400, 7600, 11000, 14200, 17400,
+ 20800, 24000, 27100, 30600, 33800,
+ 37000, 40200, 43600, 46800, 50000
+};
+
static const unsigned long max30100_scan_masks[] = {0x3, 0};
static const struct iio_chan_spec max30100_channels[] = {
@@ -243,15 +251,76 @@ static irqreturn_t max30100_interrupt_handler(int irq,
void *private)
return IRQ_HANDLED;
}
+static int max30100_get_current_idx(unsigned int val, int *reg)
+{
+ int idx;
+
+ /* LED turned off */
+ if (val == 0) {
+ *reg = 0;
+ return 0;
+ }
+
+ for (idx = 0; idx < ARRAY_SIZE(max30100_led_current_mapping); idx++) {
+ if (max30100_led_current_mapping[idx] == val) {
+ *reg = idx + 1;
+ return 0;
+ }
+ }
+
+ return -EINVAL;
+}
+
+static int max30100_led_init(struct max30100_data *data)
+{
+ struct device *dev = &data->client->dev;
+ struct device_node *np = dev->of_node;
+ unsigned int val[2];
+ int reg, ret;
+
+ ret = of_property_read_u32_array(np, "maxim,led-current-microamp",
+ (unsigned int *) &val, 2);
+ if (ret) {
+ /* Default to 24 mA RED LED, 50 mA IR LED */
+ reg = (MAX30100_REG_LED_CONFIG_24MA <<
+ MAX30100_REG_LED_CONFIG_RED_LED_SHIFT) |
+ MAX30100_REG_LED_CONFIG_50MA;
+ dev_warn(dev, "no led-current-microamp set");
+
+ return regmap_write(data->regmap, MAX30100_REG_LED_CONFIG, reg);
+ }
+
+ /* RED LED current */
+ ret = max30100_get_current_idx(val[0], ®);
+ if (ret) {
+ dev_err(dev, "invalid RED current setting %d", val[0]);
+ return ret;
+ }
+
+ ret = regmap_update_bits(data->regmap, MAX30100_REG_LED_CONFIG,
+ MAX30100_REG_LED_CONFIG_LED_MASK <<
+ MAX30100_REG_LED_CONFIG_RED_LED_SHIFT,
+ reg << MAX30100_REG_LED_CONFIG_RED_LED_SHIFT);
+ if (ret)
+ return ret;
+
+ /* IR LED current */
+ ret = max30100_get_current_idx(val[1], ®);
+ if (ret) {
+ dev_err(dev, "invalid IR current setting %d", val[1]);
+ return ret;
+ }
+
+ return regmap_update_bits(data->regmap, MAX30100_REG_LED_CONFIG,
+ MAX30100_REG_LED_CONFIG_LED_MASK, reg);
+}
+
static int max30100_chip_init(struct max30100_data *data)
{
int ret;
- /* RED IR LED = 24mA, IR LED = 50mA */
- ret = regmap_write(data->regmap, MAX30100_REG_LED_CONFIG,
- (MAX30100_REG_LED_CONFIG_24MA <<
- MAX30100_REG_LED_CONFIG_RED_LED_SHIFT) |
- MAX30100_REG_LED_CONFIG_50MA);
+ /* setup LED current settings */
+ ret = max30100_led_init(data);
if (ret)
return ret;
--
2.6.4
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